The cross-linked polymers formed by heat-curing of seven anhydrides and their eutectic mixtures with bisphenol A epoxy resin can be hydrolyzed in benzene-alcoholic sodium hydroxide solution．On aeidifying and extracting the precipitates (sodium salt of dibasic acids) which are insoluble in organic solution，their corresponding dibasic acids can be obtained．Single dibasic acid can be identified by infrared spectroscopy while mixed dibasic acids have to be differentiated by paper chromatography in isopro-panol-ammonia system．The epoxy resin cured with maleic anhydride yields fumaric acid and small amount of maleic acid upon hydrolysis and separation．The content of fumaric acid increases with elevation of curing temperature and thus proves that the occurence of this eis．trans isomerization should rather be attributed to the influence of heat during the course of cure than to the action of chemicals upon hydrolysis and aeidification．